1. Field of the Invention
This invention relates to the field of electronics. More particularly, this invention relates to electronic triggering devices. In still greater particularly, this invention relates to electronic fuze actuating systems. By way of further characterization, but not by way of limitation thereto, the invention uses a recovered doppler signal received on board a missile to establish the fuzing time of its warhead.
2. Description of the Prior Art
Fuzing time of a missile warhead is important in maximizing the effectiveness of the warhead. Because direct target contact is not always achieved, the warhead must be detonated at the next best time, that is, when the warhead is closest to the target. Since, for example, in air-to-air situations, both the missile and the target are moving at relatively high velocities with respect to one another, it is difficult to determine the optimum warhead fuzing time.
In some guided projectiles, information on relative velocities of the missile and the target is available from the guidance system by utilizing a transmitter on the launching medium. However, in a system where closing velocities are not directly available, such as a passive air-to-air missile system, it is much more difficult to accurately determine fuzing time. Additionally, since the missile guidance system itself is not used, target information must be obtained solely from the fuzing system. Since relatively short-range transmitters are used in fuzing systems, there is a relatively short time frame during which the fuzing determination must be made.
The criticality of fuzing time is especially important in a system in which the warhead is of a directional rather than a fragmentation type. Directional warheads are utilized because their energy is concentrated in a specific direction. Therefore, more accurate fuzing times are required because the effective kill area of the warhead is diminished.
Prior art fuzing systems, using recovered doppler signals, detonate the warhead once a predetermined doppler frequency has been reached. Such a device is shown in U.S. Pat. No. 3,945,008 issued to Georg Schmucker on Mar. 16, 1976. While satisfactory for its intended purpose, this system causes automatic triggering of the fuze when the doppler frequency signals reach predetermined minimum amplitudes. There is, therefore, no provisions made for changes in closing velocity and therefore accuracy may be affected. Devices using counters to effect a time delay have also been employed. One such device utilizes preset counters driven by a local oscillator device and a remote source at the point of firing. This device is shown in U.S. Pat. No. 3,670,652 issued to Richard T. Ziemba on June 20, 1972. While satisfactory for its intended purpose for surface-to-surface projectiles where one can vary the counter according to observed hit-miss data, such a fuzing device would be less satisfactory for use with swiftly moving targets and no opportunity to observe hit-miss. Other fuzing devices using counting techniques employ frequency or amplitude comparators to compare sucessive wavetrains. These devices require constant velocities and constant transmitted wave frequencies or amplitudes to function effectively. As such they are susceptible to jamming and evasive maneuvers by a moving target. Devices using multiple band-pass filters have also been used for warhead fuzing. While all of the above are satisfactory for their intended purposes a device utilizing less circuitry and having greater accuracy and sensitivity to evasive tactics by the target was needed.